This invention relates to a motor-pump unit consisting of a screw-spindle pump and having located, on the pump's pressure side, a slot-barrel motor with a rigid, preferably one-piece, motor pump shaft. In a known motor-pump unit of this type, the slot-barrel motor is connected, to the drive spindle of the screw-spindle pump with a pressure side throttle interval interposed. The shaft end of the slot-barrel motor lying spaced from the screw-spindle pump is supported within the envelope of the slot-barrel motor. Furthermore, the common drive shaft of the slot-barrel motor and screw-spindle pump is longitudinally bored through in order to relieve the interior of the slot-barrel motor from the delivery pressure of the pump. This design is highly practical for relatively large motor-pump units, but it is very expensive in the case of smaller dimensions, where the delivery pressure and also the axial thrust at the screw-spindle pump are better controllable by the structure.